Echinacea species represent one of the most widely used immunostimulatory botanicals in the United States herbal market. These products vary considerably with respect to the species used, the plant part, and the formulation. Since these different products all have distinctly different chemistries, it should not be surprising that they would exhibit different pharmacological effects. Formulation variability and therefore chemical variability contributes to the problem in interpreting clinical trials performed to date on these different preparations. It also underscores the importance of identifying the clinically relevant compounds within the different preparations so that standardized consistent products could be produced for the consumer market and for use in clinical trials. Work under our NCAAM funded R21 proposal uncovered a previously unrecognized and potent, monocyte-activating compound, that is present in high concentrations (5% of dry plant weight). A reproducible method for its extraction revealed that its activity can vary as much as 1,000 times among different plant parts of the commercially relevant Echinacea species. The main reason this potent immunostimulatory component has eluded detection is its limited solubility in solvents normally used in natural product chemistry laboratories. Our long-term working hypothesis is that this compound is a major contributor to the immune enhancing properties of this herb and together with the activities contributed by other components produce the overall therapeutic effectiveness of Echinacea. The goal of this project is to provide the means to more accurately standardize Echinacea material using this potent immunostimulatory compound so that more defined products can be used for animal research and clinical trials. It could more directly influence human health by providing information on the types of Echinacea products that contain substantial amounts of this compound (i.e. tinctures, pressed juice, plant part or species). The objectives are: 1. Determine the structural characteristics of this new compound important for activity and develop a standardization procedure 2. Evaluate the variability of this activity in commercial Echinacea plant material and preparations. 3. Investigate agronomic practices that might influence the levels and activity of this compound.